1. Field of the Invention
The present invention relates to an image blur correction apparatus which optically corrects image blur caused by vibrations.
2. Description of Related Art
A conventional image blur correction apparatus (a first conventional example) described in Japanese Patent Laid-Open No. 2002-350916 (corresponding to U.S. Pat. No. 6,606,456) has a support shaft formed on part of the periphery of a base member and a support frame (a movement member) having a long hole portion into which the support shaft is fit, wherein the base member, the support shaft, and the support frame are relatively moved on a plane substantially orthogonal to an optical axis. On the base member, two coils are disposed at positions substantially orthogonal to each other around the optical axis, and permanent magnets and yokes are disposed on the support frame opposite to the coils to constitute a magnetic circuit which serves as a drive source for the aforementioned relative movement.
Japanese Patent Laid-Open No. H11(1999)-212133 (a second conventional example, corresponding to U.S. Patent Application Publication No. 2002/0018296) has proposed an image blur correction apparatus which has a support shaft fixed to a support frame (a movement member) of the image blur correction apparatus and a base member having a long hole portion (a support shaft engaging portion) into which the support shaft is fit, wherein the support frame, the support shaft, and the base member are relatively moved on a plane substantially orthogonal to an optical axis. Similarly to the aforementioned first conventional example, coils, permanent magnets, and yokes are disposed individually to constitute a magnetic circuit serving as a drive source for the relative movement. In addition, the image blue correction apparatus has a concave portion in the periphery thereof for receiving a portion of another optical member such as a barrel extending in the optical axis direction.
Japanese Patent Laid-Open No. 2002-182259 (a third conventional example) has proposed an image blur correction apparatus which involves a relative movement on a plane substantially orthogonal to an optical axis, similarly to the aforementioned second conventional example. In the image blur correction apparatus, two coils are fixed to a support frame and disposed at positions substantially orthogonal to each other around the optical axis, and a first yoke, a pair of permanent magnets attracted to the first yoke, a second yoke, and a pair of permanent magnets attracted to the second yoke are attached to a base member opposite to the coils, thereby constituting magnetic circuit which serves as a drive source for the relative movement. The second yoke is disposed to abut on the end face of a protruding piece extending in the optical axis direction from near a long hole portion.
In the first conventional example which has the support shaft formed in the periphery of the base member, when a portion of another component of an optical device, on which the image blur correction apparatus is mounted, is disposed to cross the image blur correction apparatus in the optical axis direction, a lens barrel should be formed such that that component extends outside the periphery of the base member. This leads to an increased outer diameter of the lens barrel to cause an increase in size of the optical device.
When the image blur correction apparatus has the concave portion formed in the periphery thereof for receiving the portion of the other member extending in the optical axis direction as in the second conventional example, the long hole portion needs to be formed in the base member in accordance with the movement amount of the support frame for image blur correction, and the permanent magnets and the coils should be disposed to avoid the long hole portion, so that the space efficiency is reduced to result in an increased size of the lens barrel.
When the second yoke is disposed to abut on the end face of the protruding piece extending in the optical axis direction from near the long hole portion as in the third conventional example, the long hole portion in the base member may be pressed and deformed by magnetic attraction which acts between the second yoke and the permanent magnets. Thus, sliding friction between the support shaft and the long hole portion may be increased to reduce the drive property.